Olympic Arms K8 Magnum Targetmatch, AR, .223 WSSM

Olympic Arms K8 Magnum Targetmatch

The AR-15 and the .223 Rem. cartridge are as indelibly linked as bread and butter. But like butter in this cholesterol-phobic world, the cartridge has its critics, including me. (Photos by Bryce M. Towsley)

By Bryce M. Towsley (RSS)
June 1, 2011

For most of our shooting needs, the .223 Rem. is fine, but in my never-humble opinion, there are times when it could use a little more horsepower. The ammo makers claim a muzzle velocity of 3,240 fps with a 55-grain bullet, but I rarely see that on my chronograph screen.

High velocity would mean more energy at the target and flatter trajectories for easier long-range hits. With a 55-grain bullet, both the .22-250 Rem. and the .220 Swift achieve muzzle velocities around 3,650 fps, but both cartridges are too long to fit into an AR-15 magazine.

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The .223 WSSM, introduced in 2002, has a water capacity of 55 grains, which is considerably more than the .22-250 Rem. (44.62 grains) and the .220 Swift (46.25 grains). That means it has the potential to outperform both. It’s a rather goofy-looking cartridge, but goofy can be good. With catalog ballistics showing a muzzle velocity of 3,850 fps with a 55-grain bullet, it beats both by 200 fps. The .223 WSSM is 600 fps faster than the .223 Rem. In fact, the .223 WSSM is the fastest factory-loaded, .22-caliber cartridge available. Better yet, it will also fit in an AR-15.

Olympic Arms K8 Magnum Targetmatch, AR, .223 WSSM

The K8 Magnum utilizes a 24-inch bull barrel with a muzzle diameter of .9 inch. This rather long barrel for an AR-platform rifle allows achievement of the full potential of the .223 WSSM's speed— approaching 600 fps faster than a .223 Rem.

Olympic Arms currently offers rifles and upper receiver assemblies in all three of the WSSM cartridges: .223, .243 and .25. The company is also working on a proprietary .30-caliber super-short magnum it claims will exceed .30-06 Sprg. ballistics with a 150-grain bullet.

The .223 WSSM is only available in Olympic’s K8 Magnum Targetmatch model, both as a complete gun or as an upper receiver to fit any standard AR lower. The K8 Magnum features a 24-inch bull barrel that measures .90 inch in diameter at the muzzle. At 9.41 pounds (plus scope and ammo), the rifle is a bit heavier than I’d like for most applications.

That said, there are advantages to a heavy barrel. For example, the Targetmatch shot just as well hot as it did cold, with no change in group size as the barrel heated up.

Olympic Arms K8 Magnum Targetmatch, AR, .223 WSSM

Handling a portly cartridge necessitates a larger bolt head, stem and barrel extension. With size increases of up to 14 percent, the bolt carrier assembly and the entire upper receiver required alterations.

The black-oxide-coated, 416 stainless steel barrel has broach-cut rifling with a 1:10-inch twist rate. A low-profile gas block has a rail on top for mounting a backup iron front sight. The full-length, 12 1⁄2-inch, round, floating aluminum tube has knurling on the gripping surface. Both the upper and lower receivers are forged from 7075-T6 aluminum alloy and machined before being anodized. The ejection port in the upper receiver is enlarged to accommodate the bigger cartridge and as a result, there is no dust cover.

The bolt head is much bigger than a standard .223 Rem. bolt, measuring .1 inch larger on opposing lugs—.840 inch versus .740 inch. Despite the necessary modifications, these unique uppers will work on any standard lower.

A standard A2-style buttstock boasts a trapdoor buttplate—although Olympic offers other stock options—and the lower receiver is pretty much mil-spec. The buttstock has a sling swivel, but there is no front swivel on the rifle unless ordered as a factory option. Its grip is also the standard A2 plastic version, but, again, there are enhancements available from the factory. A mil-spec trigger, which is to say a single-stage, creepy-crawly thing that breaks at 5 pounds, 13 ounces is present. Again, Olympic offers to improve the base version. With the rapid evolution of replacement triggers for AR rifles in the past couple of years, however, I would buy one of the new drop-in triggers from Timney or American Trigger.

Magazines for the K8 Magnum are 20-round AR-15 versions modified to work as a single stack. The gun is shipped with one magazine, which holds seven of the rotund WSSM rounds. I also tested a few magazines blocked at four rounds so they are legal for hunting in my state. After firing more than 200 rounds through the magazines at random, I did not experience a single failure to feed. One problem I did have was the bolt, more times than not, failed to lock back after the last round. The magazine catch is modified to make the magazine ride lower, and I suspect that is the reason.

Olympic Arms K8 Magnum Targetmatch, AR, .223 WSSM

The feed lips and follower of a standard 20-round magazine were modified for the .223 WSSM, result- ing in a single-stack version that can accommodate the fatter cartridge.

The K8 Magnum is reliable and reasonably accurate. It offers about the same accuracy I typically see from most production bolt-action rifles chambered in this cartridge. While this test did not include any handloads, I have yet to see a rifle chambered in .223 WSSM that failed to improve in accuracy with handloads. With a better trigger, this rifle would be an excellent choice for any shooter looking to upgrade the performance of the .223 Rem.

Manufacturer: Olympic Arms; (800) 228-3471
Action Type: Gas-operated, semi-automatic
Caliber: .223 WSSM
Capacity: 7 rounds
Receiver: Black-anodized, forged and machined 7075-T6 aluminum alloy
Stock: Synthetic, A2-style
Barrel: 24 inches; 416 stainless steel
Rifling: Broach-cut; 4 grooves; 1:10-inch RH twist
Sights: None; Picatinny rail for mounting optics
Trigger Pull Weight: 5 pounds, 13 ounces
Overall Length: 42 1⁄2 inches
Weight: 9.41 pounds
MSRP: $1,363.70

Olympic Arms K8 Magnum Targetmatch, AR, .223 WSSM

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